Reaction of the Phosphenium Complexes Cp(OC)2W=P(tBu)(R) with Ethyl Isothiocyanate: Unprecedented Formation of the Phosphametalla Spiro Compound {Cp(OC)2W–P(tBu)(R)–N(Et)–Ca[N(Et)–(CH)–N(Et)CbH2]–S(W–S)(Ca–Cb)}Cl (R =tBu, Ph)

Abstract

Reaction of the phosphenium complexes Cp(OC)2W=P(tBu)(R) [R = tBu (2a), Ph (2b)] with ethyl isothiocyanate (3) leads to the formation of the phosphametallacycles Cp(OC)2W–P(tBu)(R)–C(=NEt)–S(W–S) (4a, b) by [2 + 2] cycloaddition. In contrast, the “in situ” reaction of 2a, b, generated from Cp(OC)2[H(tBu)(R)P]W–Cl (1a, b) with DBU in the presence of 3 leads to the spirocyclic phosphorus metal compounds {Cp(OC)2W–P(tBu)(R)–N(Et)–Ca[N(Et)–(CH)–N(Et)CbH2]–S(W–S)(Ca–Cb)}Cl (6a, b). The structure of 6a has been proved by X‐ray analysis.

Cycloaddition Reactions of the Phosphinidene-Bridged Complex [Mo2Cp(μ-κ1:κ1,η5-PC5H4)(CO)2(η6-HMes*)] with Diazoalkanes and Other Heterocumulenes

“…The bridging ligand in complex 3 is a phosphinidene–isothiocyanate adduct (RP·C­(S)­NR), of which we can quote no previous examples. However, this ligand defines a PCSMo metallacycle completely analogous to those present in the complexes obtained in reactions of the mononuclear phosphanyl complexes [ML­(PR 2 )­(CO) 2 ] with different isothiocyanates (M = Mo, W; L = Cp, Cp*; R = Ph, H, t Bu) . These metallacyclic complexes in turn are models of the intermediates presumably formed in reactions of other mononuclear phosphanyl complexes which end up with full insertion of the added isothiocyanate into the Mo–P bond of the parent substrate …”